Genomic biobank research, like much scientific and biomedical research, aims to produce generalizable knowledge of collective benefit to humans and possibly other living organisms. Direct benefit to individual participants is not a paramount goal, if a goal at all. But this raises ethical concerns. Biobank research may uncover medically significant information. Some have argued that there is an ethical duty to inform individual participants of such findings. In this project, I will develop a presumptive case against returning any individual results to subjects in biobank research. First, I will critically examine the claim that it is morally obligatory to disclose individual results. Utilizing the framework of negative and positive duties, I will explore the philosophical foundations of five different principles that might underwrite such a duty - non-maleficence, respect for persons, beneficence, reciprocity, and the duty to warn or rescue. While these principles are often cited in the debate, little attention has been given to philosophical complexities or qualifications. Considered with more rigorous scrutiny, each principle fails to support a moral obligation to return individual results. Second, I will critically examine the weaker claim that, even if it is not obligatory, returning at least some individual results would be morally good or at least morally permissible. Against these more moderate claims, I will explore how returning individual results in biobanking would disproportionately burden limited research resources and introduce at least six significant costs and risks. A policy of never returning results would reduce or eliminate all six of these costs and risks and outweigh the potential benefits of even selective returns of individual results. Finally, I will identify and consider potential solutions for any significant practical challenges that might be encountered when individual results are not returned. Given that some participants will desire access to these results, and others may implicitly expect to receive them, careful consideration needs to be given as to how to ethically and effectively communicate to potential research participants the rationale for withholding all individual results. Additionally, there will be important questions about how this rationale can be operationalized within the informed consent process. I will consider these and other challenges and offer recommendations about how best to meet them. PUBLIC HEALTH RELEVANCE: This project will critically examine the claim that researchers in large biorepositories have an ethical duty to inform participants of at least some individual results. To do this, I will first analyze the basis for thinking that any actions are morally obligatory or morally good and then apply this to the unique situation of biorepository research. I will develop an argument against returning any individual results to study subjects and recommend policies and regulations for effectively putting this into practice.